Centre for Internet & Society

This chapter deals with frequently asked questions relating to difference between IPTV and mobile television, IPTV and Internet television, difference between broadcast and unicast methods of television, additional support required for handsets to support MBMS, etc.

Mobile Television

What is the difference between IPTV and Mobile Television?
Mobile Television is the availability of regular television channels to view on your mobile. The bandwidth available in a wireless network is variable, also, the mobile device sizes are not standardized, and hence the technology requires support to adapt to these varied conditions. On the contrary, IPTV usually uses a reliable and controlled medium like fixed line broadband, or cable as a medium of transmission. It also assumes that the service provider offers some guarantees on the bandwidth allocated for television.

What is the difference between IPTV and Internet television?
Internet television refers to television/video service provided over the internet. In the case of Internet television, the content is streamed over the Web just like any other multimedia service. The internet is characterized by lack of guarantees about the bandwidth, although the variability is less than in the case of mobile networks.  Internet television uses unicast point to point streaming because it is a service accessed by individual users from anywhere in the network.

On the contrary, IPTV usually uses a reliable and controlled medium like fixed line broadband, or cable as a medium of transmission. IPTV uses IP multicast over a controlled network with a set of users specifically subscribed to the service. Mobile television and internet television (television viewing on the PC using an internet connection) are also sometimes referred to as Over the Top or unmanaged television.

Which is the difference between broadcast and unicast methods of television?
Broadcast method of television allows multiple users to receive the same transmission from the source, while unicast television is a point to point method where a stream is sent to each user separately.

Which is a better mode of television – broadcast or unicast?
Ideally a combination of the two modes allows maximum flexibility and efficiency. Unicast television makes sense where each user gets personalized services like Video on Demand, recording of programs and so on. Broadcast television is more efficient when many people in the same area are viewing a popular program at the same time. IPTV uses broadcast/multicast technology for the live television and common television channels, and the unicast method for the personalized services.

What are the various technologies defined for mobile broadcast television?
Some of the technologies defined for mobile broadcast television include MediaFlo (A Qualcomm standard), Digital Video Broadcasting (DVB-H), Multimedia Broadcast and Multicast Services (MBMS), Enhanced MBMS (e-MBMS) and Advanced Television Committee Standards (ATSC). Of these, e-MBMS is the latest technology expected to see mass adoption in the future, while DVB-H has been deployed in some places in Europe and MediaFlo in the US in the past. Of these technologies, MediaFlo is a proprietary technology; MBMS has been created by 3GPP, while the DVB-H and ATSC come as an evolution of traditional television standards.

What additional support is required for the handsets to support MBMS?
The handsets should be able to read three control channels defined for MBMS, which indicate the availability of MBMS, understand the frame structure of the transmission, and read the actual broadcast data. It should also support OMA BCAST, which is a standard defined for the Electronic Service Guide (ESG) and renders the television programming guide information.

Are there any MBMS compliant handsets in the market?
MBMS has been trialed by many operators starting from 2007; however, commercial deployments of MBMS have not been announced. It is expected that some of the LTE operators in Asia, especially densely populated countries like India and China will launch MBMS. There are no commercially available handsets that support MBMS in the open market. The handsets used are expected to be custom made and bundled with LTE subscriptions.

Are any additional network elements needed to support MBMS?    
An element called BMS-C (Broadcast Multicast Service Center) is introduced; this manages subscription, billing and session information for MBMS. Other network elements like MCE (Multi-cell Coordination Entity) are also required for multi-cell broadcast, in LTE networks, where multiple cells are coordinated to retransmit the same information. More details will be discussed in the technical module 2.8.6.

Where are the standards for MBMS defined?
MBMS was introduced in Release 6 of 3GPP specs, but has been defined in more detail in Release 9, in conjunction with LTE.

Additional Reading: http://bit.ly/LUloxu

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